(1) Field of the Invention
The present invention pertains to a cleaning system for a sheet metal conditioning apparatus. More specifically, the present invention pertains to a cleaning and recycling system for liquid used in a sheet metal surface conditioner that conditions sheets. of metal received from a stretching-leveling machine.
(2) Description of the Related Art
A wide variety of manufactured goods are constructed with processed sheet metal. For example, aircraft, automobiles, and home appliances, to name only a few, contain parts that are formed from processed sheet metal. These parts are formed by a stamping and/or blanking operation performed on the sheet metal.
Virtually all stamping and/or blanking operations performed on sheet metal require a flat sheet. However, sheet metal is typically purchased from steel mills and/or steel service centers as elongate sheets that have been rolled into large rolls for storage and shipping efficiency. Before the sheet metal can be used in the manufacturing of products, the sheet metal from the roll must be flattened. The surfaces of the sheet metal must also be conditioned to provide the product component part manufactured from the sheet metal with smooth surfaces.
One example of an apparatus that processes sheet metal is described in the U.S. Pat. of Voges No. 6,205,830 B1, which issued on Mar. 27, 2001, and is incorporated herein by reference. The apparatus described in this patent combines a stretching-leveling machine with a surface conditioning system. The stretching-leveling machine stretches sheet metal passed through the machine. The sheet metal is stretched beyond its yield point to provide a flat sheet of metal and to eliminate internal residual stresses from the sheet of metal. The stretching-leveling machine then discharges the stretched sheet of metal to the sheet metal surface conditioning system.
The surface conditioning system includes a surface conditioner that receives the sheet metal from the stretching-leveling machine and passes the sheet metal through a series of rotating brushes that engage the surfaces of the sheet metal. The rotating brushes remove scale and other smut from the surfaces of the sheet metal. A coolant/lubricant, for example water, is applied to the brushes during the cleaning operation to produce a cooler running operation, to wash away the scale and smut removed from the surfaces of the sheet metal, and to extend the useful life and effectiveness of the brushes.
Typically, the coolant/lubricant liquid is dispensed from a plurality of sprayer nozzles. The sprayer nozzles are spatially arranged along a spray bar that extends across the width of the sheet metal being passed through the sheet metal surface conditioner. Depending on the width of the sheet metal being processed, the sprayer bars positioned above and below the sheet metal passed through the surface conditioner have four or more sprayer nozzles spatially arranged along each bar. In addition, the typical sheet metal surface conditioner employs a plurality of sprayer bars positioned both above and below the sheet metal being passed through the surface conditioner. The coolant/lubricant is supplied to the sprayer nozzles of the surface conditioners at a rate of about 180 gallons per minute. This results in a substantial amount of coolant/lubricant conditioning liquid being dispensed in the sheet metal surface conditioner. This conditioning liquid is then removed from the sheet metal surface conditioner, with the scale and smut removed from the surfaces of the sheet metal being carried away by the conditioning liquid.
This prior art method of conditioning the surfaces of sheet metal is disadvantaged in that it requires a substantial amount of water. The cost of supplying a large amount of water to the surface conditioner adds to the cost of processing the sheet metal.
Disposing of the conditioning liquid contaminated by the scale and smut removed from the sheet metal also presents a sizeable problem. The contaminated conditioning liquid can be piped to a large retention pond where the scale and smut contaminating the conditioning liquid will settle down to the bottom of the pond over time. The somewhat cleaner conditioning liquid can then be piped off or hauled to a water treatment site or to a sewage site. However, this method of disposing of the contaminated conditioning liquid requires a large area adjacent to the metal processing facility for the retention pond.
Alternatively, the contaminated conditioning liquid can be shipped in large tanker trucks to a waste water treatment site. However, the use of large tanker trucks to dispose of the contaminated conditioning liquid adds to the cost of processing the sheet metal.
The present invention provides a cleaning and recycling system for the conditioning liquid used in sheet metal surface conditioners that overcomes the problems associated with sheet metal surface conditioners of the prior art. The cleaning and recycling system continuously reuses a large portion of the conditioning liquid that has been contaminated by the scale and smut removed from sheet metal without requiring a large settling pond by the sheet metal processing facility.
The cleaning and recycling system of the invention is employed with a sheet metal conditioner that has a first set of conditioning liquid dispensers that function primarily to assist the brushes of the conditioner to remove the scale and smut from the surfaces of the sheet metal, and a second set of conditioning liquid dispensers that function primarily to rinse the sheet metal before it is discharged from the sheet metal surface conditioner. Both the first and second sets of liquid dispensers dispense a coolant/lubricant liquid, typically water, onto the sheet metal as it passes through the rotating brushes of the sheet metal surface conditioner.
The conditioning liquid contaminated by the scale and smut removed from the sheet metal is removed from the sheet metal surface conditioner by the cleaning and recycling system of the invention. The conditioning liquid contaminated with the scale and smut is directed through a first filter where a substantial portion of the scale and smut is removed from the conditioning liquid. The conditioning liquid that passes through the first filter is then collected in a recycling tank.
A substantial portion of the liquid contained in the recycling tank is then pumped back to the sheet metal surface conditioner. The conditioning liquid that has passed through the first filter is pumped to the first set of liquid dispensers of the sheet metal surface conditioner where the primary function of the liquid is to cool and lubricate the brushes of the surface conditioner and to carry away the scale and smut removed from the surfaces of the sheet metal by the brushes. The cleanliness of the conditioning liquid is not of primary importance for performing this function.
The cleaning and recycling system of the invention also includes a second filter that communicates with the conditioning liquid in the recycling tank through a metered valve. A portion of the conditioning liquid collected in the recycling tank is pumped through the metered valve and through the second filter which further filters smaller particles of the scale and smut from the conditioning liquid that were not removed by the first filter. The liquid that passes through the second filter is then directed back to the sheet metal surface conditioner where the liquid is dispensed from the second set of liquid dispensers. This second set of liquid dispensers rinses the surfaces of the sheet metal just before it is discharged from the sheet metal surface conditioner. For the rinsing function performed by the second set of liquid dispensers, the cleanliness of the conditioning liquid is of greater importance. The liquid dispensed by the second set of liquid dispensers in the surface conditioner, having been passed through both the first and second filters of the filtering and recycling system, is cleaner than the liquid dispensed by the first set of liquid dispensers which has only been passed through the first filter.
Thus, the cleaning and recycling system of the invention continuously reuses the conditioning liquid that has been contaminated with scale and smut removed from sheet metal passed through the sheet metal surface conditioner and overcomes the problems associated with prior art sheet metal surface conditioners.